This invention relates to ram air parachutes, and more particularly to an improved ram air parachute canopy having a crescent shaped planform and rib spacing that varies from the central region of the parachute toward the side edges.
Ram air inflated air foil canopies for glide parachutes are well known and are constructed of upper and lower spaced flexible fabric surfaces connected by ribs or webs of flexible material extending longitudinally in the direction of flight when the parachute is deployed in use. The flexible upper and lower surfaces and ribs form collapsible elongated ram air cells usually extending from the leading edge to the trailing edge of the parachute. These cells are automatically opened and maintained open by ram air entering the cells through the leading edge, or more recently, adjacent the leading edge on the under surface of the canopy.
Early examples of such parachutes are shown in U.S. Pat. Nos. 3,724,789 (Snyder), RE 26,427 (Jalbert), and 3,524,613 (Reuter); and more recently, in U.S. Pat. Nos. 4,705,238 (Gargano), 4,708,078 (Legrignoux), 4,424,945 (Dell), 4,771,970 (Sutton), and 4,811,910 (Askwith). The teachings of these prior patents are incorporated herein by reference. It is well known that such prior art designs have induced drag and instability due to the rectangular planform shapes, uniformly shaped cells and uniformly spaced ribs across the width of the parachute.